Method of stabilizing trichloroethyl-



United States PatentO METHOD OF STABILIZING TRICHLOROETHYL- AND STABILIZING COMPOSITION THERE- Germano Patron and Antonio Ferri, Milan, Italy,

assignors to Sicedison Sct., Milan, Italy No Drawing. Filed Dec. 17, 1958, Ser. No. 780,957 Claims priority, application Italy June 13, 1958 6 Claims. (Cl. 260652.5)

The present invention relates to a method of stabilizing trichloroethylene and to a stabilizing composition therefor.

It is known that trichloroethylene is utilized industrially in various technical processes, particularly as a solvent for degreasing metals. Since trichloroethylene is an unstable chemical compound, the solvent is easily decomposed during such processes. The phenomena of decomposition of trichloroethylene are enhanced by the presence of air, light, moisture andheat, particularly.

when the solvent is in contact with metallic surfaces, such as iron and aluminum- As these phenomenaar e'ofi'an autocatalytic nature, it is most important to effectively stabilize the solvent, especially in view of the fact-that the hydrochloric .acid formed by the decomposition of trichloroethylene develops fonexample in steel or alumi= num articles, which are beingpdegreased, thejchloridejof these metals," which chlorides, in turn, enhance very much thedecomposition process of "the solvent under' formation of more hydrochloric acid andlsubseque'nt strong corrosion of the metallic articles being degreas ed.

It is known in the art to use various types of organic substances for stabilizing trichloroethylene, such as the amines, phenols, alcohols, epoxides and esters; these subcomposition of thelatter vwhenus'ed in processes for, de-

greasing metals. s

It is another object of our invention toimprove the conditions of working with trichloroethyl'ene asla solvent by providing a method and stabilizing composition which suppress the accumulation of acid'products in trichldrb ethylene or neutralizesthe same when formed.

The objects of ourinvention are attained with the aid of our technically improved method of stabilizing tri ice ideneazine, and dimethylketazine, and is admixed to trichloroethylene in amounts of from 0.01% to 0.02% b weight approximately.

The epoxide may be, for instance, one of the group comprising butylene oxide, propylene oxide, amylene oxide, or chloropropylene oxide and is added to trichloroethylene in amounts of'fromn0.2% to 0.3% by weight approximately.

The alcohol may be one of the groupcomprising isobutyl alcohol, butyl alcohol, propyl alcohol, isopropyl alcohol, amyl alcohol, isoamyl alcohol, ethyl alcohol, and may be added to trichloroethylene in amounts of from 0.05% to 0.1% by weight approximately.

The phenolic compound may be chosen from the grou comprising phenol, thymol, ortho-nitrophenol, eugenol, is0propyl-p-hydroxyanisol, ethyl-p-hydroxyanisol, and should be added to trichloroethylene preferably in quan tities of from 0.005 to 0.01% by weight approximately.

The quantities of the components of the synergetic mixture may be chosen larger or smaller than the amounts given above depending upon the stabilizing effects to be attained and according to the other adjuvants which may be present in the solvent.

Such adjuvants are mentioned in our copendihg appii cation Serial No. 747,566, filed July 18, 1958, now abandoned, and maybe for instance, esters or alcohols" and the like compounds which may be added'tothe tiichloroethylene degreasing solvent without afiecting intrinsically or substantially the synergetic effect of the quaternary mixture of the present invention. i

The synergetic mixture according to the invention may contain one or several substances for each'type of the components mentioned further above, and. chosen-from the list of substances mentioned for each type. 1 For .example, the group of the phenols may be represented the synergetic mixture not only by phenol itself, but may also consist of a mixture of phenol and th'ymol; as reprlesentative of the class of epoxides, a mixture of propyl ene oxide and butylene oxide may be added, and the' same applim to the other two groups, to be present as components in the synergetic mixture.

The technical advantages achieved with the present in:

vention are illustrated by the following test series in which" samples of" trihlorqethyleryi, s ebi ils. b 'yasili me h: ods, are classified according to their stability properties as revealed on the basis of a 48-hour accelerated oxidation test as specified in U.S.A. Army-Navy-Aeronautical Specification MILT70 03 and Fede r al Specification OT- chloroethylene which makes use of a heretofore unknown synergetic mixture. 7

Our invention is based on thediscovery that it is possible to produceasynergetib action of stabilizing trichloroethylene when a quaternary combination is added to trichloroeithylene, the mixture containing a hydrazine derivative, 'an epoxide, an alcohol and-a phenolic comw h" The hydrazine, derivative may .be one of the group werei NNiiPifllYlllYdWH? zae na i fl This stability test consists essentially in causing 200 m1. of trichloroethylene to. boil for 48 hours in a Pyr'ex flask of 500 ml. with reflux condenser and causinga stream of gaseous oxygen saturated'with watertd bubble through the solvent in the flask byway ot a glas'sltiibQe having: a diameter of 3 mmL at a speed of 10 61-2; bubbles per minute; a b x 2 x94 inch SAE, steel strip is suspended inthe vapor "phase whilefa A'x x inch SAE steel strip is introduced "intofthefflask .iiijthe liquid ase a 1'50 ,w.'- frosted light bulb is used.- but s he a agre nether At the end of the test, the acidity of the trichloroethylene isdetermined. The percentages of the various adjuvants are given by weight. The pH values are determined in the aqueous extracts of trichloroethylene after the completion of the stability test by using in each case the same ratio of waterztrichloroethylene of 1: 1. All of the tests were repeated two or three times and the results averaged.

TEST SERIES I Examples 115 This test series was conducted to demonstrate the stabilizing action of the synergetic mixture of butylene oxide and isobutyl alcohol+phenol-l-N,N-dimethylhydrazine. Table I shows the results of the tests on the basis of Examples 1 through 15: Examples 1 to 4 were carried out with individual stabilizing compounds; Examples 5 to with binary mixture, Examples 11 to 14 with ternary mixtures and Example 15 finally with the quaternary mixture according to our present invention. It will be noted from the results shown in Table I that the pH value of the trichloroethylene samples stabilized with individual stabilizing compounds or with binary and ternary mixtures is much lower than 7.0 and thus noticeably acid, whereas the pH value of the sample stabilized with the quaternary mixture of butylene oxide+, isobutyl alcohol+phenol+N,N-dimethylhydrazine remains practically neutral after the completion of the stability test.

TABLE I pH of trlchloro- Sample ethylene No. Stabilizers added to trichloroethylene after accelerated oxidation N,N-dimethylhydrazine 0.01% 1-2 Butylene oxide 0.2% 7-2. Isobutyl alcohol 0.07% 7-2. Phenol 0.01% 0-2. p N,N-dimethylhydrazine 0.01%+butylene oxide 3-2.

0. 6; N ,N-dimethylhydrazine 0.01%+isobutyl alcohol N,N-dimethylhydrazine 0.01%+phenol 0.01% Butylene oxide 0.2%+isobutyl alcohol 0.07%- Butylene oxide 0.2%+phenol 0.01% Isobutyl alcohol 0.07%+phenol 0.01% N,N-dimethylhydrazine 0.01%,-|-buty1ene oxide 0.2%+isobutyl alcohol 0.07%. N,N-dimethylhydrazine 0.01%+butylene oxide 3. 4-3. 7

0.2%+phenol 0.01%. N,N-dimethylhydrazine 0.0l%+isobutyl al- 3.2-2.6

cohol 0.07%+phenol 0.01%. Buiiylenleooglige 0.2%+isobutyl alcohol 0.07%+ 2. 5-2. 8 p eno 15 N,N-dimethyl hydrazlne 0.01%+buty1ene oxide 6.6-7.0 0.2%+isobutyl alcohol 0.07%+phenol 0.01%.

TEST SERIE II Examples 16-30 TABLE II 1311 of trichloro- Sample ethylene No. Stabilizers added to trichloroethylene after accelerated oxidation test N,N-dimethylhydrazine 0.01% 1- Propylene oxide 0.2%. Isobutyl alcohol 0.07%.

2. 4 l. 2 1. 7 0 o-Nitrophenol 0.01% 2. 7- 9 N ,N iimethylhydrazine 0.01%+propylene oxide 2. 1- 4 0.2 NbN-Zdimethylhydrazine 0.01%+isobutyl alcohol 2. 3-2. 6

.0 N,N-d7imethy1hydrazine 0.01%+o-nitrophenol 2. 5-2. 8

0.01 Propylene oxide 0.2%+isobutyl alcohol 0.07%.-. 2. 9-3. 2 Propylene oxide 0.2%+n-nitrophenol 0.01% 1. 9-2. 2 Isobutyl alcohol 0.07%+o-nitrophenol-0.01%- 2. 0-2. 2 N,N-dimethylhydraziue 0.0l%+propylene oxide 3. 7-4. 0

0.2%+isobutyl alcohol 0.07%. N,N-dimethylhydrazine 0.01%+propylene oxide 4. 2-4. 5

0.2%+o-nitrophenol 0.01%. N,N-dimethylhydrazine 0.0l%+isobutyl alcohol 3. l-3. 3

0.07%+o-nitr0phenol 0.01%. Propylene oxide 0.2%+isobutyl alcohol 0.07%+ 2.1-2.3

o-nitrophenol 0.01%. N,N-dimethy1hydrazine 0.01%+propylene oxide 6. 5-7. 0

0.2%+isobutyl alcohol 0.07%+o-nitrophenol 0.01%.

We claim:

1. A trichloroethylene composition stabilized against acidic decomposition, particularly during its use for degreasingmetals, which comprises small quantities, intimately mixed and synergetically active, of N,N-dimethylhydrazine, isobutyl alcohol, butylene oxide, and phenol.

2. A stabilizing composition for trichloroethylene comprised of a synergetic mixture, of from about 1 to portions by weight of N,N-dirnethylhydrazine, from about 10 to 100 portions by weight of isobutyl alcohol, from about 1 to 100 portions by weight-of phenol, and from 10 to 1000-portions by weight of butylene oxide.

3. A trichloroethylene composition stabilized against acidic decomposition, particularly during its use for the degreasing of metals, which comprises small quantities, intimately mixed and synergetically active, of N,N-dimethylhydrazine, isobutyl alcohol, propylene oxide and onitrophenol.

4. A stabilizing composition for trichloroethylene comprised of a synergetic mixture of item about 1 to 100 parts by weight of N,N-dimethylhydrazine, from about 10 to 100 parts by weight of isobutyl alcohol, fi'om about 1 to 100. parts by weight of o-nitrophenol and from 10 to 1000 parts by weight of propylene oxide.

5. A method of stabilizing trichloroethylene for preventing its acidic decomposition, especially during the degreasing of metals, comprising the step of intimately mixing to the trichloroethylene small quantities of a synergetic quaternary mixture of N,N-dimethy1hydrazine, isobutyl alcohol, butylene oxide and phenol.

6. A method of stabilizing trichloroethylene for preventing its acidic decomposition, especially during the degreasing of metals, comprising the step of intimately mixing to the trichloroethylene small quantities of a synergetic quaternary mixture of from about 1 to 100 parts by weight of N,N-dimethylhydrazine, from about 10 to 100 parts by weight of isobutyl alcohol, from about 1 to 100 parts by weight of phenol and from about 10 to 1000 parts by weight of butylene oxide.

References Cited in the tile of this patent UNITED STATES PATENTS 2,008,680 Carlisle et a1. July 23, 1935 2,043,257 Missbach June 9,, 1936 2,371,644 Eetering et al. Mar. 20, 1945 2,797,250 Copelin June 25,1957

I FOREIGN PATENTS 787,726 Great Britain Dec. 1-1, 1957 

1. A TRICHLOROETHYLENE COMPOSITION STABILIZED AGAINST ACIDIC DECOMPOSITION, PARTICULARLY DURING ITS USE FOR DEGREASING METALS, WHICH COMPRISES SMALL QUANTITIES, INTIMATELY MIXED AND SYNERGETICALLY ACTIVE, OF N,N-DIMETHYLHYDRAZINE, ISOBUTYL ALCOHOL, BUTYLENE OXIDE, AND PHENOL.
 3. A TRICHLOROETHYLENE COMPOSITION STABILIZED AGAINST ACIDIC DECOMPOSITION, PARTICULARLY DURING ITS USE FOR THE DEGREASING OF METALS, WHICH COMPRISES SMALL QUANTITIES, INTIMATELY MIXED AND SYNERGETICALLY ACTIVE, OF N,N-DIMETHYLHYDRAZINE, ISOBUTYL ACOHOL, PROPYLENE OXIDE AND ONITROPHENOL. 